Official Docs: GlideDate

The scoped GlideDate class provides methods for performing operations on GlideDate objects, such as instantiating GlideDate objects or working with GlideDate fields

getByFormat

Gets the date in the given date format

getMonthNoTZ

Returns the month part of a date with no timezone conversion

getValue

Gets the date value stored in the database by the GlideDate object in the internal format, yyyy-MM-dd, and the system time zone, UTC by default

getYearNoTZ

Returns the year part of a date with no timezone conversion

subtract

Gets the duration difference between two GlideDate values

getDisplayValue

Gets the date in the current user's display format and time zone

setValue

Sets the date of the GlideDate object

getDisplayValueInternal

Gets the display value in the internal format (yyyy-MM-dd). Note: This method is useful for date or time fields, but not date fields

getDayOfMonthNoTZ

Returns the day part of a date with no timezone conversion

setDisplayValue

Sets a date value using the current user's display format and time zone